The study was conducted by researchers at the Ottawa Hospital Research Institute, headed by Dr. John Bell, who has been researching oncolytic viruses for more than 10 years, along with Dr. David Kim from San Francisco. Together, they developed JX-594, which originated from another virus used in a live smallpox vaccine. The researchers genetically altered JX-594 so that it would effectively target only cancer cells and multiply within them, thereby killing the cancer cells.

Researchers used five different dosages of the virus to inject 23 cancer subjects. After 10 days, 87 percent of those who received the two highest dosages (7 persons) showed evidence of virus replication within their tumors, but no replication in healthy tissue. The virus was generally accepted well by all subjects, with the most common side effect being flu-like symptoms for a day or so.

Intravenous injection of JX-594 was critical to the success of the virus as a treatment for metastasized cancer because it is the only method that allows multiple tumors to be reached..

"Oncolytic viruses are unique because they can attack tumors in multiple
ways, they have very mild side effects compared to other treatments,
and they can be easily customized for different kinds of cancer," said Dr. Dell. "We're
still in the early stages of testing these viruses in patients, but I
believe that someday, viruses and other biological therapies could truly
transform our approach for treating cancer."